变速介质条件下三维叠前深度偏移成像及应用效果

对于复杂变速介质成像，常用的时间域成像方法已不能满足实际需要，必须借助于深度域成像方法，特别是三维地震叠前深度偏移方法。选择合适的深度偏移方法很重要，但其速度模型建立更为关键。叠前深度偏移与速度建模均需要巨大的计算机资源，为有效地实现三维叠前深度偏移，合理的处理流程与方法选择也十分重要。文章从叠前深度偏移方法原理比较分析入手，深入探讨了相关深度偏移方法的特点，并对速度模型建立方法进行了研究。在此基础上，结合一个横向变速的三维地震工区实例，详细论述了横向变速条件下三维叠前深度偏移的建模思路与实现方法，提出了先进、实用的有关叠前深度偏移与速度建模实用方法。实际偏移结果与井资料的一致性证明了上述方法的有效性和实用性，这对推进三维叠前深度偏移的应用与发展并取得良好的成像效果具有较大的实际意义。

3-D Prestack Depth Migration for Variable Velocity Media and Its Application

The conventional imaging methods in time domain can not meet the practical requirements for variable velocity complex media, and we have to do the imaging in depth domain, especially do 3-D prestack depth migration. Selecting the proper depth migration method is very important, and building accurate velocity model is even more crucial. Moreover, both of them need the massive computer resources, so the reasonable processing flow and method also is a key for fulfilling 3-D prestack depth migration effectively. Starting with comparison and analysis of the principle of various prestack depth migration methods, the paper thoroughly discussed the characteristics of each method, and researched new methods of velocity model building. Then, the paper detailedly explained the idea and implementation approach of velocity model building in 3-D prestack depth migration by a case of 3-D seismic exploration in a working area with lateral velocity variations. Finally, a series of advanced and practical methods related to prestack depth migration and velocity model building and minimizing computer resource are presented in the paper. That the migration result of the real data are in good agreement with the drilling result shows the methods mentioned above are effective and practical, and it is very significant for improving the application and development of 3-D prestack depth migration and obtaining good seismic imaging effects.